1. Field of the Invention
The present invention relates to a digital video recording/reproduction apparatus and a program therefor. More particularly, the present invention relates to a digital video recording apparatus for recording on a recording medium a digital broadcast program received by a digital broadcast receiver, and a program for realizing the recording processing, and also to a digital video reproduction apparatus for reproducing a digital broadcast program recorded on a recording medium, and a program for realizing the reproduction process.
2. Description of the Background Art
As is well known in the art, a digital broadcast receiver receives a digital broadcast signal in which a plurality of programs are multiplexed, and decodes a selected one of the programs so as to reproduce the program by means of a monitor and/or a loudspeaker. In order to allow a selected program to be recorded on a predetermined recording medium (e.g., a magnetic tape medium such as DVHS tape, or an optical disk such as a DVD), a digital broadcast receiver also outputs a signal representing the program to a digital video recording/reproduction apparatus via a digital interface. The output to a digital video recording/reproduction apparatus is in the form of a partial transport stream (hereinafter referred to as a “partial TS”).
A partial TS includes packets composing video and audio elementary streams and packets containing predetermined information tables (control data). Hereinafter, an “elementary stream” will be abbreviated as “ES”.
Information tables to be contained in a partial TS may be in data formats such as a Program Association Table (hereinafter abbreviated as “PAT”) and a Program Map Table (hereinafter abbreviated as “PMT”) as defined under STD-B10, and a Discontinuity Information Table (hereinafter abbreviated as “DIT”) and a Selection Information Table (hereinafter abbreviated as “SIT”) as defined under STD-B21, both proposed by the ARIB (Association of Radio Industries and Businesses).
FIGS. 12 to 15 illustrate the respective information table formats.
As shown in FIG. 12, a PAT contains a service identifier (program_number) of a service to be carried via a given partial TS (hereinafter referred to as a “target service”), a packet identifier of a PMT (program_map_PID: hereinafter abbreviated as “PMT_PID”), and the like. As shown in FIG. 13, a PMT contains a service identifier (program_number) of a target service, a packet identifier of a program clock reference (hereinafter abbreviated as “PCR”) (PCR_PID), a packet identifier of a TS packet which carries the ES or payload of a target service (elementary_PID: hereinafter abbreviated as “ES_PID”), and the like. A DIT is to be inserted where a partial TS becomes discontinuous or where the number of ES's contained in a given partial TS increases or decreases. As shown in FIG. 15, a DIT contains a transition flag (transition_flag) which represents the type of change occurring in the transport stream.
A conventional digital video recording/reproduction apparatus which utilizes magnetic tape as a recording medium records a digital broadcast program received by means of a digital broadcast receiver in such a manner that, each time recording is started, a DIT is recorded at the beginning of each recorded region to indicate a discontinuity in the recorded programs. FIG. 16A schematically illustrates how DIT's may be recorded a recording medium in the case where program B is recorded following program A.
When a recording medium on which programs are recorded in this manner is reproduced through the discontinuous portion, a conventional digital video recording/reproduction apparatus detects the recorded DIT and knows that programs have been recorded in a discontinuous manner based on the content of the DIT. Then, the conventional digital video recording/reproduction apparatus redetects video information and audio information which are necessary for reproduction, as well as a PCR for synchronizing the video information with the audio information. Thus, the conventional digital video recording/reproduction apparatus is controlled so that a reproduction process can properly occur when going through a discontinuous portion.
In the above-described conventional digital video recording/reproduction apparatus, DIT's are recorded only at the beginning of recording. Therefore, while a discontinuous portion can be properly detected if programs are recorded on a recording medium program without overlap, such is no longer the case if a new program is overwritten on an already-recorded region. For example, as shown in FIG. 16B, if a new program C is overwritten part of the way down a program A and part of the way into the following program B, then a DIT which was recorded at the beginning of program B will be erased. Thus, a conventional digital video recording/reproduction apparatus has a problem in that, when program C and program B are consecutively reproduced, the discontinuous portion between program C and program B cannot be properly detected, making it impossible to allow a proper reproduction process to occur for the remaining recorded portion of program B.
One cure for this problem might be recording a DIT at the end of recording also. However, such technique would result in a waste of recording area on the recording medium. Moreover, there is a problem with respect to responsiveness to a user in that, when an instruction to stop recording is issued by a user, the recording operation can stop only after a DIT is recorded.